The principal objectives of the proposed research are (a) to investigate the structure and dynamics of the DNA-dependent RNA polymerase, and other related control proteins (b) to resolve the complex processes of RNA synthesis into their elementary steps, and (c) to elucidate the resulatory mechanism of gene transcription. We propose to approach these objectives by various physicochemical methods, in particular, fast kinetics, nanosecond fluorescence spectroscopy and various cross-linking techniques. In this way, both structural and dynamic information will be yielded. Studies will be carried out primarily with the Escherichia coli system because large quantities of the highly purified RNA polymerase and the various components of the control system of lac operon can be obtained. The problems to be investigated include: (1) the structural and functional relationships among the multiple binding sites of RNA polymerase, (2) the spatial organization and biological assembly of the subunits of RNA polymerase, (3) the kinetics and thermodynamics of the interactions between RNA polymerase, DNA template, and nucleoside triphosphates, and of the formation of phosphodiester bonds in RNA polymerase, (4) the syncatalytic mapping and the translocation of the enzyme during the course of RNA synthesis, (5) the role of sigma subunit and other regulatory factors in gene transcription and (6) the molecular mechanisms involved in the positive and negative control of transcription of the lac operon. The ultimate goal of this study is to understand the mechanism and regulation of gene expression in molecular detail.